Production of greases using reaction products of alpha-hydroxy fatty acids



and the resulting cooled material is :then ,to produce asmooth: grease;

Patented Feb. 17, 1953 UNITED STATES PATENT OFFICE PRODUCTION "OFGREASES 'USIN G REAG- .TION- PRODUCTS F- ALPHA-.HYDROXY FATTY ACIDSWilliam Bpwhitney, Bartlesville, 0kla., assignmto Phillips PetroleumCompanypa corporation oflDelaware yNoiDrawing. Application'March17,1950,

. Serial No. 150,355

smoothgrase with little tendency to bleed.- .In

l14'Claims. (01.252441) '2 I have also found that the "reaction product,formed. upon esterifieation of the hydroxy group of the'hydroxyfattyacid'with one or more molecules of such an acid, when convertedto ametal salt, is an excellent gelation agent forlubricat- *ingoil greases.

Thus, accordin to the invention, ajuncture I product of a hydroxy fattyacid, preferably an still another of itsaspects the invention relates.to noveligel type lubricatin greases having. little te'ndencyto bleed.It is well known that greases can be made by dissolving :or dispersingunder suitable conditions a "fatty acidsoap in a suitable hydrocarbonoil The particular type of grease produced'depends, of course, upon themethod by which it is produced. A fiber grease isusually produced byl'IllX- ing th'e proper? proportions of oil,ifat, andaqueous causticsoda'and heating to saponify the fat and to evaporate the water formedas .well'as any duced by slow cooling and mixing withadditional oil.Agel grease is produced by mixing a suitable fatty'acid soap, usually inan amountfrom 5 to per cent, witha hydrocarbon oil and heating to atemperature somewhat above the solution temperature. Upon effectingsolution, the mate- :rialiscooled sufiiciently rapidly thatsubstantiallyino separationof. soap and. oil takes place, worked ;Inmaking.:ge1 greases, the soap'is usuallyan alkali metal :salt of afatty. acidof 18 carbon atoms or higher. The "sodium and potassium saltsof 'palmitic acid (16 carbon atoms) can only occasionally be used, .andthose of less than 16 carbon atoms do not appear to be compatible withthe oils insofar asmakinggrease isconcerned.

Lithium salts of fatty acids having 16, 14, and

.sometimes .12 carbon atoms per molecule can often be used. The oil usedin the 'manufacture of the grease determines how short a chain can besuccessfully used.

[I have now found thatmetal salts of jthereac- 'tion'pro'cluct of anhydroxy fatty acid, especially alph'a-hydroxy fatty acid, with "at leastone-other molecule of such an acid, and/or with another fatty acid, isproduced; converted to a metal salt and then used in the production-of agel type lu'bricating grease. In place of the fatty acidother acylatingagents can also *be used. For example, the acid anhydrides -or the-acidchlorides of the fatty acids can be used. Also a polymerized hydroxyfatty acid can 'be reacted to "form a mixture of a metal saltof thepolymer and a metal salt of a fatty acid and-said'mixturecan-thenbe-usedas a grease gelation'agent.

The following description and examples read in conjunction with thepreceding portion 'of-this specification will indicate fully and clearlythe scope of theappendecl claims to the invention so that one skilled inthe grease production art will be enabledto prepare any of the productsto which reference is made. A now-preferred elation agent of the"invention is that which is formed by the reaction of analpha-hydroxyfatty acid with a fatty acid. Therefore, the following portion ofthe'descriptionrelates-to said reaction.

The general process for the production'of the gelation agents from analpha-hydroxy fatty'acid and a fatty acid comprisesheating the fattyacid and alpha-hydroxy-fatty acid'in the liquid phase "for a sufiicientlength of time to efiect'reaction,

usually from 1 to 12 hours. A condensation'cata- "lyst suchas zincchloride'can be used. [Thereac- Operation at atmospheric pressure isordinarily preferred, but elevated pressure can be used Where necessary.

The reaction which takes place, at least 'to a large extent-appears tobe ROOOH +R'CHOHCOOH R-CH,COOH +"H,o

Rooo wherein R and "R' represent alkyl-grou and total numberofcarbonatomsin R'+R is: at 'leas "16 and 'preferably'at leas't 18.

Several specific procedures, not necessarily either as separate streamsor as a mixture.

molecule.

completely equivalent methods, for carrying out the reaction can beused. In some instances one or more of these methods will be found to bepreferred over another.

The simplest method for carrying out the illustrated reaction is to heata mixture of the fatty acid and hydroxy fatty acid, the fatty acid beingpresent at least in an amount molecularly equivalent to the hydroxyfatty acid. The product is then neutralized to produce the sodium salt,and the neutral product is used to produce a gel grease with ahydrocarbon oil.

In a second method, the reaction vessel initially contains only a heatedquantity of fatty acid, and the alpha-hydroxy fatty acid is then slowlyadded with agitation. In this manner, the concentration of the reactivehydroxy acid is kept low and the reaction is directed toward juncture ofthe fatty acid and hydroxy fatty acid, because the opportunity for twohydroxy fatty acid molecules to react has been minimized. After thereaction has been effected, neutralization of the acid constituents toform sodium salts and the making of the grease is carried out.

The reaction may also be carried out in a continuous system. In such amethod, the fatty acid and hydroxy fatty acid are continuously chargedto a reaction zone in the desired proportions, A stream of the reactionmixture equal to the materials charged is continuously drawn off.Neutralization and making of the grease is carried out as before.

In some instances, it may be desirable to effect even further directionof the reaction to that of the fatty acid with the alpha-hydroxyl group.This may be done by maintaining at all times the fatty acid in molecularexcess over the unreacted alpha-hydroxy fatty acid in the reaction zone.The excess fatty acid may be removed from the reaction mixture,withdrawn and recycled to the reaction zone prior to neutralization.However, in those instances where this excess is not objectionable inthe final utilization, none or only a part may be removed prior toneutralization.

In choosing the starting reactants, it is desirable to choose a pairwhich will yield a juncture product of at least 16 carbon atoms permolecule, and preferably 18 or more carbon atoms per As noted,. apartial esterification of the alpha-hydroxy fatty acid with itself canoccur. However, these dimers should be considered on the basis of totalavailable monomer,

disregarding any dimerization, when calculating the moles in any givenquantity of hydroxy fatty acid. 7

Although not as desirable a method as those previously described, analpha-hydroxy fatty acid can be polymerized and subsequently reacted toform a mixture of the sodium salts of the polymer I acid that may beconverted to a soap suitable for use in a grease.

These gelation agents can also be used with the synthetic ester, diesterand polyester lubricating oils, or with polyalkalene oxide lubricatingoils,

although it is noted especially that an ester oil is no t required andthat according to the inven- 4 tion greases with lubricating oils can beprepared with little or no working by simple admixture and heating ofthe gelation agent and a lubricating oil.

It is to be noted thatthe gelation agents of this invention producegreases of excellent resistance to bleeding.

Example I Example II In a second trial, it was attempted to produce agel grease from the mixed sodium salts of lauric acid andalpha-hydroxydecanoi-c acid. This mixture of salts did not produce agrease. These salts individually are not gelation agents.

Example III In another test, alpha-hydroxydecanoic acid as the onlyreactant was heated for three hours at C. and one hour additional at'200 C.

The resulting material was neutralized with sodium hydroxide and thissodium salt mixed with sodium laurate. The mixed salts were then usedsuccessfully as a gelation agent in making a gel grease from ahydrocarbon oil.

Example IV Portions of alpha-hydroxydecanoic acid were separatelyreacted by the previously-described procedure in mixture with stearicacid and in mixture with oleic acid. Each product was converted to thesodium salt and then successfully used as the gelation agent for makinga gel grease from hydrocarbon oil.

From Examples I and II it can be noted that the neutralized reactionproduct of lauric acid and alpha-hydroxydecanoic acids acted as agelation agent whereas a mixture of the sodium salts of these acids didnot so act. However, in Example III, where the alpha-hydroxydecanoicacid was the only reactant and it was reacted with itself, thenneutralized and then mixed with sodium laurate a successful gelationagent was obtained. Example IV shows that substitution of stearic andoleic acids, respectively, for the lauri-c acid of Example I wassuccessful.

Although this specification is directed mainly to the use of sodiumsoaps of the disclosed condensed acids, it should be understood thatother metal soaps may be used. These include soaps of other alkalimetals, suchas potassium and lithium, soaps of the alkaline earthmetals, such as calcium, strontium, and barium, and also soaps ofaluminum and of magnesium. The soaps of the difierent metals are notnecessarily full equivalents, and this fact must be borne in mind whenspecific applications of the invention are contemplated. Mixtures of thesoaps of two or more metals may be used as grease gelation agents withinthe broad scope of this invention.

- Other alpha-hydroxyacids usable in the process of the invention arealpha-hydroxyoctanoic acids, alpha-hydroxydodecanoic acids,alpha-hydr-oxy hexadecanoic acids.

Variation and modification are possible within the scope of theforegoing disclosure and the appended claims to the invention theessence of which is that certain hydroxy fatty acid, preferablyalpha-hydroxy fatty acid, reaction products have been prepared, and whenconverted to sodium salts, these products have been found to producesmooth gel type lubricating greases with little or no working beingrequired and the grease having little or no appreciable tendency tobleed; this without necessary recourse to any ester oil.

I claim:

1. The production of a gel type lubricating grease which compriseseffecting an esterification juncture of an hydroxy fatty acid with atleast one of an hydroxy fatty acid and another fatty acid to produce ajuncture product having at least sixteen car's-on atoms to the molecule;converting the juncture product to a metal salt; and admixing said saltwith a suitable lubricating oil to produce said grease.

2. A production according to claim 1 wherein the juncture is effected atan elevated temperature suilicient to cause reaction to occur and thereaction mass is maintained at said temperature for a time suflicient tocomplete the reaction.

3. A production according to claim 2 wherein the temperature is in therange 125 to 250 C.

4. A production according to claim 3 wherein the temperature initiallyis lower than finally and the initial temperature is maintained for asubstantial period of the reaction.

5. The production of a gel type lubricating grease which compriseseffecting an esterification juncture of alpha-hydroxydecanoic acid(2-hydroxy-4,6,6-trimethylheptanoic acid) with at least one materialselected from the group consisting of said acid itself and another fattyacid to produce a juncture product having at least sixteen carbon atomsto the molecule; converting the juncture product to sodium salt; andthen admixing said salt with a suitable lubricating oil to produce saidgrease.

6. A production according to claim 5 wherein the other fatty acid whenused is selected from the group consisting of lauric, stearic and oleicacids.

7. A production according to claim 6 wherein the juncture is effected ata temperature in the approximate range 125 to 250 C.

8. A gel type lubricating grease the essential gelation agent of whichis a metal salt of an and 'esterificatiorri-juncture product of anhydroxy fatty acid with a material selected from the group consisting ofan hydroxy fatty acid and another fatty acid said product containing atleast sixteen carbon atoms.

9. A grease according to claim 8 consisting essentially of said gelationagent and a suitable lubricating oil.

10. A grease according to claim 8 wherein the hydroxy fatty acid is2-hydroxy-4,6,G-trimethylheptanoic acid and the other fatty acid isselected from the group consisting of lauric, stearic and oleic acids.

11. A gel type lubricating grease the gelation agent of which is anadmixture of the sodium salt of an esterificati on juncture product ofalphahydroxydeoanoic acid (2-hydroxy-4,6,6-trimethylheptanoic acid) withitself and sodium laurate.

12. The preparation of a gel-type lubricating grease which comprisesheating an hydroxy fatty acid with at least one of an hydroxy fatty acidand another fatty acid, in the liquid phase at-a temperature in theapproximate range -250 0., for a time in the range of from about 1 hourto about 12 hours, to produce a product having at least 16 carbon atomsto the molecule; converting the product thus produced to a metal salt;admixing the salt thus obtained with a lubricating oil; heating theadmixture to form a blend of said salt and said lubricating oil; andthen cooling said blend sufficiently rapidly, so that no substantialseparation of the salt and oil can occur, to form said grease.

13. A preparation according to claim 12 wherein the hydroxy fatty acidis at least one acid selected from the group consisting ofalpha-hydroxy-octanoic acid, alpha-hydroxydecanoic acid,alpha-hydroxydodecanoic acid, and alpha-hydroxyhexadecanoic acid and thesaid another fatty acid is at least one acid selected from the J groupconsisting of lauric acid, palmitic acid,

stearic acid and oleic acid.

14. A preparation according to claim 12 in which a small amount of zincchloride is employed as a catalyst during the first heating step.

WILLIAM B. WHITNEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,927,296 Powers Sept. 19, 19332,334,274 Meadows Nov. 16, 1943 2,375,530 De Groote et al. May 8, 19452,397,956 Fraser Apr. 9, 1946 2,450,220 Ashburn et al Sept. 28, 19482,452,092 Ault Oct. 26, 1948 FOREIGN PATENTS Number Country Date 615,188Great Britain Jan. 3, 1949

1. THE PRODUCTION OF A GEL TYPE LUBRICATING GREASE WHICH COMPRISESEFFECTING AN ESTERIFICATION JUNCTURE OF AN HYDROXY FATTY ACID WITH ATLEAST ONE OF AN HYDROXY FATTY ACID AND ANOTHER FATTY ACID TO PRODUCE AJUNCTURE PRODUCT HAVING AT LEAST SIXTEEN CARBON ATOMS TO THE MOLECULE;CONVERTING THE JUNCTURE PRODUCT TO A METAL SALT; AND ADMIXING SAID SALTWITH A SUITABLE LUBRICATING OIL TO PRODUCE SAID GREASE.